Trace Minerals Role in CWD Discounted

REGINA- Mar 16/04 - SNS -- Levels of trace minerals such as copper and manganese, which play a vital role in the function of an important nervous system protein called the prion, do not appear to have any direct impact on an animal's susceptibility to chronic wasting disease (CWD).

Researchers suspected their might be a link because the abnormal form of prion can be passed from one animal to another and cause CWD. For these reasons, researchers at the Western College of Veterinary Medicine (WCVM) undertook a project that examined the possible influence of trace minerals on an animal's susceptibility to CWD, says Dr. Peter Flood, professor emeritus in WCVM's Department of Veterinary Biomedical Sciences.

"In March and October, 2001, more than 1,200 farmed elk from different locations in Saskatchewan were slaughtered because they belonged to herds affected by CWD. We examined liver and brain samples from 216 of these animals: 53 of them were positive for CWD and, for each of these 53, we had control samples from three healthy animals. All samples were analyzed for copper, manganese, magnesium, iron, molybdenum and zinc," says Flood.

The final report on this project, which was supported by the Agriculture Development Fund (ADF), states that the levels of copper and manganese in the livers of CWD positive and negative elk were remarkably similar. No statistical difference between them could be demonstrated. The same was true for copper and manganese concentrations in brain tissue.

"We concluded that, at least within affected farms, the status of copper and manganese does not influence susceptibility to CWD. This conclusion does not mean trace minerals have no effect on an animal's susceptibility to CWD but, if there is an effect, it is small. I believe we successfully promoted the view that CWD is a complex problem, and that a role for minerals does not exclude or weaken the current view that the primary cause of the disease is an infectious protein, a prion," says Flood.

One other important finding of the project, while having no bearing on the final conclusions, was the fact that the mineral status of animals varied widely from farm to farm. By current standards, in fact, the elk on several farms were mineral deficient, which suggests that, in some cases, the animals' nutrition could be improved, says Flood.

A copy of the ADF project The Influence of Trace Minerals on Susceptibility to Chronic Wasting Disease (CWD), ##035;20010027, is available by phoning 306-787-5929 in Regina. The final copy is also available on the Saskatchewan Agriculture, Food and Rural Revitalization Web site.

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